Liquid crystal display device

ABSTRACT

It is an object of the present invention to provide a method for manufacturing a thin phase difference film of a liquid crystal display easily so as not to prevent a liquid crystal from being driven so that cost for manufacturing a liquid crystal display is reduced. A liquid crystal display device according to the present invention has a structure in which phase difference films that have the same function as a conventional phase difference film are formed by using a liquid crystal stabilized with a polymer over a first substrate and a second substrate that have electrodes formed thereover, and a liquid crystal material is interposed between these substrates. In addition to the structure, it is also a feature that the phase difference film formed over the substrate is formed by using a liquid crystal that is stabilized with a polymer including a conductive material.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device, andfurther, to technology of an optical film, and more particularly, aphase difference film of a liquid crystal display device.

2. Related Art

In recent years, demand for a liquid crystal display device as a flatpanel display has grown since the liquid crystal display device hasadvantages of thinness, lightweight and being capable oflow-power-consumption driving. The liquid crystal display has variousmodes, and liquid crystal displays using a nematic liquid crystalinclude a twisted nematic (TN) mode, a vertical alignment (VA) mode, anin plane switching (IPS) mode, an optically compensated bend (OCB) modeand the like. Further, a ferroelectric liquid crystal mode and anantiferroelectric liquid crystal mode in which a response speed isfaster than in a nematic liquid crystal are also proposed.

In addition, many other modes are proposed. However, when a liquidcrystal display is used as a display, phase difference films 701 areprovided outside a liquid crystal 702 and substrates 703 as shown inFIG. 12 not to generate viewing angle dependency of transmitted lightintensity and a color. Further, polarizing plates 700 are providedoutside the phase difference films 701. This phase difference film 701is also referred to as an optical compensation film or a phasedifference plate.

Although it depends on a liquid crystal mode or a liquid crystal to beused, as for a phase difference film that is used for a liquid crystaldisplay, a uniaxial film and a biaxial film may be stacked.

This phase difference film is usually manufactured by uniaxial orbiaxial drawing of a plastic film.

As another method, a phase difference film is also manufactured by usinga discotic liquid crystal as described in Patent Document 1.

However, these phase difference films are attached to the outside asubstrate so that an adhesion layer is necessary for the phasedifference films. In addition, TAC (cellulose triacetate) is necessaryto protect the phase difference films. Therefore, in order tomanufacture a phase difference film, a structure of several layersstacked is employed, and thus, the thickness is submicron, which resultsin high cost.

On the other hand, it is also reported that a phase difference film isplaced inside a liquid crystal cell in order to reduce cost. (Refer to,for example, a Non-Patent Document 1)

This method provides the following advantages; namely, strongfilm-adhesiveness, more lightness in weight, and the thinner thicknesssuch as 1 μm to 5 μm.

However, this method is a manufacturing method for only a uniaxial film,and a manufacturing method for a biaxial film has not yet been madeclear.

In addition, even when the same uniaxial film is used, it is necessaryto change the thickness in order to change a phase difference, since aphase difference is usually determined by Δn×d in the case where thebirefringence of a phase difference film is Δn and the thickness is d.

In accordance with this method, a phase difference film is placedbetween an electrode and a liquid crystal that are provided inside asubstrate. Therefore, although the thickness of a phase difference filmis thinner, namely 1 μm to 5 μm, the thickness of the liquid crystal is1.5 μm to 6 μm, and thus, there is caused a problem that voltage is noteasily applied to the liquid crystal as compared with a case where thephase difference film is provided outside the substrate.

[Patent Document 1]

-   Japanese Patent Application Laid-Open No.: Hei8-50206

[Non-Patent Document 1]

-   B. M. I. van der Zande et al, SID DIGEST, p 194-197 (2003)

SUMMARY OF THE INVENTION

In view of the problems as described above, it is an object of thepresent invention to provide a method for manufacturing a thin phasedifference film of a liquid crystal display easily so as not to preventa liquid crystal from being driven so that the cost for manufacturing aliquid crystal display is more reduced than conventionally.

In order to solve the problems as described above, a liquid crystaldisplay device according to the present invention has a structure inwhich, over each of a first substrate and a second substrate that has anelectrode formed thereover, a phase difference film that has the samefunction as a conventional phase difference film is formed by using aliquid crystal stabilized with a polymer and a liquid crystal materialis interposed between the first and second substrates.

In addition to the structure described above, it is also a feature thatthe phase difference film formed over the substrate is formed by using aliquid crystal stabilized with a polymer including a conductivematerial.

In an aspect of the present invention, a liquid crystal display deviceincludes a first substrate, a first electrode formed over the firstsubstrate, a first orientation film formed over the first electrode anda first phase difference film formed over the first orientation film,and a second substrate provided with a second electrode, a secondorientation film, and a second phase difference film, where a liquidcrystal is interposed between the first phase difference film formedover the first substrate and the second phase difference film providedwith the second substrate.

In addition, in the aspect described above, a liquid crystal stabilizedwith an acrylic resin is used for the first phase difference film andthe second phase difference film.

In addition, in another aspect of the present invention, the first phasedifference film and the second phase difference film are patterned.

In addition, in another aspect of the present invention, each of thefirst phase difference film and the second phase difference film has atleast two films.

In addition, in another aspect of the present invention, a conductivematerial is included in the first phase difference film and the secondphase difference film.

In the case of a liquid crystal display device according to the presentinvention as described above, a phase difference film can be providedbetween an electrode and a liquid crystal, further, the problem of athick film caused in manufacturing a conventional phase difference filmis solved, and thus, it is possible to provide a liquid crystal displaydevice including an inexpensive phase difference film manufacturedwithout preventing a liquid crystal from being driven.

Moreover, since phase difference films can be stacked, phase differencefilms for various liquid crystal modes can be designed.

These and other objects, features and advantages of the presentinvention will become more apparent upon reading of the followingdetailed description along with the accompanied drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a liquid crystal display deviceaccording to the present invention.

FIGS. 2A and 2B are schematic diagrams of a liquid crystal displaydevice according to the present invention.

FIGS. 3A and 3B are schematic diagrams of a liquid crystal displaydevice according to the present invention.

FIGS. 4A and 4B are schematic diagrams of a liquid crystal displaydevice according to the present invention.

FIGS. 5A to 5E are diagrams illustrating examples of electronic devices.

FIG. 6 is a diagram illustrating one example of electronic devices.

FIGS. 7A and 7B are diagrams illustrating one example of electronicdevices.

FIG. 8 is a diagram illustrating one example of electronic devices.

FIG. 9 is a diagram illustrating one example of electronic devices.

FIG. 10 is a diagram illustrating one example of electronic devices.

FIGS. 11A to 11C are diagrams illustrating examples of electronicdevices.

FIG. 12 is a diagram illustrating a structure of a conventional liquidcrystal display device.

DESCRIPTION OF THE INVENTION

Embodiment Modes of the present invention will be described below.

Embodiment Mode 1

A liquid crystal display device will be described with reference to FIG.1, and FIGS. 2A and 2B here.

In the present embodiment mode, as shown in FIG. 1, phase differencefilms 101 are provided inside substrates 103, and a liquid crystal 102is provided inside the phase difference films 101. In addition,polarizing plates 100 are provided outside of the substrates 103.

Hereinafter, a passive matrix type will be explained with reference toFIGS. 2A and 2B. FIG. 2A is a top view of a liquid crystal displaydevice and FIG. 2B is a cross-sectional view of the liquid crystaldisplay device shown in FIG. 2A along B-B′. A transparent electrode 510is provided over a first substrate 501 and an orientation film 503 isprovided thereover, for which a rubbing process is conducted. Theorientation film 503 and the rubbing process are necessary orunnecessary depending on a liquid crystal mode that is used.

Further, a phase difference film 520 formed by using a liquid crystalthat is stabilized with a polymer (also referred to as apolymer-stabilized liquid crystal) is provided over the orientation film503. For the phase difference film 520, a liquid crystal is mixed intoan UV-cured resin material that includes a photopolymerizationinitiator, and irradiated with ultraviolet light to be polymerized. Theliquid crystal used here may be a nematic liquid crystal, aferroelectric liquid crystal or an antiferroelectric liquid crystal.When the thickness of the phase difference film is made thin, a liquidcrystal material that has a large Δn may be mixed therein. Moreover, achiral agent may be mixed therein if necessary. It is to be noted thatan acrylic resin can be used as the UV-cured resin material. As for themixing ratio of the UV-cured resin material and the liquid crystal, theratio of the liquid crystal is preferably less than 50 wt %, since apolymer region is narrowed so that the phase difference film is no morea film when the ratio of the liquid crystal is high.

In order to obtain a uniaxial phase difference film, a nematic liquidcrystal that includes no chiral agent may be mixed into an UV-curedresin material. In addition, in order to obtain a biaxial phasedifference film, a ferroelectric liquid crystal, an antiferroelectricliquid crystal or a chiral agent may be mixed into an UV-cured resinmaterial. Alternatively, these liquid crystals and the agent may becombined. In addition, a conductive material may be mixed therein. It isto be noted that a metallic particle such as Au can be used as theconductive material. The ratio of a conductive material included in thephase difference film is preferably 10 wt % or less to keep transparenceof the phase difference film.

It is not always necessary that the liquid crystals mixed in the phasedifference film 520 and a phase difference film 521 and a liquid crystal507 interposed between the first substrate and a second substrate be thesame. Since a phase difference is determined by Δn×d, the types of theliquid crystals and a light-transmitting resin are appropriatelyselected with respect to a phase difference to be obtained. In thatcase, an anisotropic resin may also be used. It is to be noted that d isless than 1 μm. In addition, it is preferable that the surface of thephase difference film be coated with a light-transmitting resin.

As a method for applying the polymer-stabilized liquid crystal thatforms the phase difference film 520, a dropping method, spin coating,ink-jet, dye coating, wire-bar coating, glass-bar coating or the likecan be used.

The polymer-stabilized liquid crystal is applied and then irradiatedwith UV light under a nitrogen atmosphere to be polymerized. Ifnecessary, a rubbing process may be conducted after the UV irradiation.

Also over the second substrate 502 that serves as an opposed substrate,in the same manner as the first substrate 501, a transparent electrode511 and an orientation film 504 are provided and a rubbing process isconducted. Also, as for this orientation film 504, the orientation film504 and the rubbing process are necessary or unnecessary depending on aliquid crystal mode that is used. Further, the phase difference film 521formed by using a polymer-stabilized liquid crystal is provided in thesame manner as the first substrate 501.

Although not illustrated here, a columnar spacer is provided over thesecond substrate 502. The column spacer keeps a gap between the firstsubstrate 501 and the second substrate 502, and a bead spacer may alsobe used. In addition, in a small-area liquid crystal display device, aspacer is not always provided.

A sealant 505 is applied to the first substrate 501 or the secondsubstrate 502, and the first substrate 501 and the second substrate 502are attached to each other. The shape of the applied sealant 505 dependson a method for injecting the liquid crystal 507. In the case of anormal vacuum-injecting method, the sealant 505 has a shape with oneopening; however, in the case of a method of dropping and vacuum-bonding(One Drop Filling: ODF), the sealant 505 needs to have a loop shape withan opening closed.

The liquid crystal 507 is injected between the first substrate 501 andthe second substrate 502. The liquid crystal 507 is normally injected invacuum. When the liquid crystal is not injected in vacuum, the injectionis conducted by using capillarity under the condition where the sealanthas two or more openings. When the liquid crystal 507 is injected by amethod of dropping and vacuum-bonding, the liquid crystal 507 is droppedto the first substrate 501 or the second substrate 502 before the firstsubstrate 501 and the second substrate 502 are attached to each other,and then, the substrates are attached in vacuum.

Then, the first substrate 501 and the second substrate 502 are cut tohave a panel shape. When the sealant has an opening at this point, theopening is filled with a sealing material. Moreover, the first substrate501 and the second substrate 502 are appropriately provided with apolarizing plate 515 in order to enhance contrast.

As a liquid crystal mode for the liquid crystal display device in thepresent embodiment mode, a TN mode, an STN mode, an IPS mode, a VA mode,a ferroelectric liquid crystal mode, an antiferroelectric liquid crystalmode, an OCB mode, a birefringence mode, a guest host mode, a dynamicscattering mode, a phase transition mode and the like can be applied. Inaddition, the display device can be applied to any of a transmissiontype, a reflection type, and a semi-transmission type.

As described above, the phase difference film formed by using thepolymer-stabilized liquid crystal is provided inside the panel, and thephase difference film can be thin. Therefore, a liquid crystal displaydevice which does not prevent a liquid crystal from being driven can beprovided.

Embodiment Mode 2

In the present embodiment mode, a case where the phase difference filmin Embodiment Mode 1 is patterned will be described with reference toFIGS. 3A and 3B.

As for a first substrate 601 in FIG. 3B, the manufacturing process isthe same as in Embodiment Mode 1 until an orientation film 603 isprovided. The orientation film 603 and the rubbing process are necessaryor unnecessary depending on a liquid crystal mode that is used.

Further, a patterned phase difference film 620 formed by using apolymer-stabilized liquid crystal is provided. When a UV-cured resinmaterial is cured by UV irradiation under a nitrogen atmosphere, alight-shielding mask that has an opened portion corresponding to atransparent electrode 610 is used so that only a pixel region isirradiated with ultraviolet light. Therefore, the phase difference film620 formed by using the polymer-stabilized liquid crystal is providedonly over the transparent electrode 610. A portion that is notirradiated with ultraviolet light except the pixel region is washed withacetone or the like after the UV irradiation. After the UV irradiation,the rubbing process is conducted if necessary.

As for a second substrate 602 that serves as an opposed substrate, themanufacturing process is the same as in Embodiment Mode 1 until anorientation film 604 is provided. Over the orientation film 604, a phasedifference film 621 formed by using a polymer-stabilized liquid crystalis provided over a transparent electrode 611 that is a pixel region.

A sealant 605 is applied to the first substrate 601 or the secondsubstrate 602, and the first substrate 601 and the second substrate 602are attached to each other. The shape of the applied sealant 605 dependson a method for injecting a liquid crystal 607. In the case of a normalvacuum-injecting method, the sealant 605 has a shape with one opening;however, in the case of a method of dropping and vacuum-bonding, thesealant 605 needs to have a loop shape with an opening closed.

Then, the liquid crystal 607 is injected between the first substrate 601and the second substrate 602. The liquid crystal 607 is normallyinjected in vacuum. When the liquid crystal is not injected in vacuum,the injection is conducted by using capillarity under the conditionwhere the sealant has two or more openings. When the liquid crystal 607is injected by a method of dropping and vacuum-bonding, the liquidcrystal 607 is dropped to the first substrate 601 or the secondsubstrate 602 before the first substrate 601 and the second substrate602 are attached to each other, and then, the substrates are attached invacuum.

Then, the first substrate 601 and the second substrate 602 are attachedas in Embodiment Mode 1 and cut. Further, the first substrate 601 andthe second substrate 602 are appropriately provided with a polarizingplate 615 in order to enhance contrast.

As a liquid crystal mode for the liquid crystal display device in thepresent embodiment mode, a TN mode, an STN mode, an IPS mode, a VA mode,a ferroelectric liquid crystal mode, an antiferroelectric liquid crystalmode, an OCB mode, a birefringence mode, a guest host mode, a dynamicscattering mode, a phase transition mode and the like can be applied. Inaddition, the display device can be applied to any of a transmissiontype, a reflection type, and a semi-transmission type.

As described above, the phase difference film formed by using thepolymer-stabilized liquid crystal is provided inside the panel, andpattering is conducted only for a minimally required pixel region.Therefore, a liquid crystal display device that uses this phasedifference film can be formed even when adhesiveness of the phasedifference film and the sealant is bad. The yield of a liquid crystaldisplay device can be improved by using a phase difference film that hasthis shape.

Embodiment Mode 3

In the present embodiment mode, a case where phase difference films arestacked over a substrate ail substrate) over which a thin filmtransistor (TFT) is formed will be described with reference to FIGS. 4Aand 4B.

FIG. 4A shows a liquid crystal display device in which a signal linedriving circuit 1200, a scanning line driving circuit 1201, and a pixelregion 1202 are formed over a first substrate 1210.

FIG. 4B is a cross-sectional view of the liquid crystal display devicein FIG. 4A along A-A′, and shows the signal line driving circuit 1200provided with a CMOS circuit that includes an n-channel TFT 1223 and ap-channel TFT 1224 over the first substrate 1210. The n-channel TFT 1223and the p-channel TFT 1224 are formed by laser annealing with the use ofa pulse laser to have a crystalline semiconductor film in which crystalgrains are aligned. It is particularly preferable to form a channelforming region from one crystal grain. The TFTs which form the signalline driving circuit 1200 and the scanning line driving circuit 1201 maybe formed by using a CMOS circuit, a PMOS circuit or an NMOS circuit.Further, an FPC 1209 connected to a connecting wiring 1208 is formedover the first substrate 1210.

The pixel region 1202 includes a switching TFT 1211 and a capacitorelement 1245. The switching TFT 1211 is formed by laser annealing withthe use of a pulse laser to have a crystalline semiconductor film inwhich crystal grains are aligned. It is particularly preferable to forma channel forming region from one crystal grain. The capacitor element1245 is formed by a gate insulating film that is interposed between asemiconductor film doped with an impurity and a gate electrode. It isunnecessary that a TFT in the pixel region 1202 has high crystallinityas compared with the signal line driving circuit 1200 and the scanningline driving circuit 1201. The pixel region 1202 includes a pixelelectrode 1250 that is connected to one electrode of the switching TFT1211, and an insulator 1214 is provided to cover the n-channel TFT 1223,the p-channel TFT 1224, the pixel electrode 1250 and the switching TFT1211. Then, an orientation film 1206 is provided, and a rubbing processis conducted. The orientation film 1206 and the rubbing process arenecessary or unnecessary depending on a liquid crystal mode that isused.

Further, a patterned first phase difference film 1260 is provided. Therubbing process is conducted to the first phase difference film 1260 ifnecessary, and a second phase difference film 1261 is provided in thesame manner as the first phase difference film 1260. If necessary, arubbing process is conducted after UV irradiation.

A second substrate 1204 that serves as an opposed substrate is providedwith a black matrix 1253 at the position which overlaps with the signalline driving circuit 1200 and a color filter 1252 at the position whichoverlaps with at least the pixel region 1202. Then, the second substrate1204 with an opposed electrode 1251 formed thereover is provided with acolumnar spacer 1255. The columnar spacer 1255 keeps a gap between thefirst substrate 1210 and the second substrate 1204, and a bead spacermay also be used. In addition, in a small-area liquid crystal displaydevice, a spacer is not always provided.

In addition, an orientation film 1207 is provided, and a rubbing processis conducted. As for this opposed substrate, similarly to the firstsubstrate, the orientation film and the rubbing process are necessary orunnecessary depending on a liquid crystal mode that is used.

Further, the first phase difference film 1260 and the second phasedifference film 1261 are provided over the second substrate 1204 as inthe case of the first substrate 1210. The phase difference films 1260and 1261 are not necessarily composed of two layers, and may have threeor more layers if necessary. Moreover, in the case of a reflection typeliquid crystal display device, only the second substrate 1204 thatserves as an opposed substrate may have a phase difference film.

A sealant 1205 is applied to the first substrate 1210 or the secondsubstrate 1204, and the first substrate 1210 and the second substrate1204 are attached to each other. The shape of the applied sealant 1205depends on a method for injecting a liquid crystal 1256. In the case ofa normal vacuum-injecting method, the sealant 1256 has a shape with oneopening; however, in the case of a method of dropping andvacuum-bonding, the sealant 1256 needs to have a loop shape with anopening closed.

The liquid crystal 1256 is injected between the first substrate 1210 andthe second substrate 1204. The liquid crystal 1256 is normally injectedin vacuum. When the liquid crystal is not injected in vacuum, theinjection is conducted by using capillarity under the condition wherethe sealant has two or more openings. When the liquid crystal 1256 isinjected by a method of dropping and vacuum-bonding, the liquid crystal1256 is dropped to the first substrate 1210 or the second substrate 1204before the first substrate 1210 and the second substrate 1204 areattached to each other, and then, the substrates are attached in vacuum.

Then, the first substrate 1210 and the second substrate 1204 are cut tohave a panel shape. When the sealant has an opening at this point, theopening is filled with a sealing material. Moreover, the first substrate1210 and the second substrate 1204 are appropriately provided with apolarizing plate 1270 in order to enhance contrast.

As a liquid crystal mode of a liquid crystal display device in thepresent embodiment mode, a TN mode, an STN mode, an IPS mode, a VA mode,a ferroelectric liquid crystal mode, an antiferroelectric liquid crystalmode, an OCB mode, a birefringence mode, a guest host mode, a dynamicscattering mode, a phase transition mode and the like can be applied. Inaddition, the display device can be applied to any of a transmissiontype, a reflection type, and a semi-transmission type.

As described above, since the polymer-stabilized liquid crystals,namely, the phase difference films are stacked inside the panel, it ispossible to stack a uniaxial film and a biaxial film, stack differentuniaxial films, or stack different biaxial films. Therefore, a liquidcrystal display device that has a wide application range can beprovided.

Embodiment Mode 4

A liquid crystal display device that is formed by implementing any oneof Embodiment Modes 1 to 3 described above can be applied to variouselectronic devices. In other words, the liquid crystal display devicecan be incorporated in a display portion of electronic devices as willbe described below.

Electronic devices as described above include a TV set, a video camera,a digital camera, a projector, a head mount display (a goggle-typedisplay), a car navigation system, an in-car audio system, a personalcomputer, a personal digital assistant (such as a mobile computer, acellular phone, or an electronic book) and the like. FIGS. 5A to 5E andFIG. 6 show specific examples of these electronic devices.

FIG. 5A is a TV set, which can be manufactured by incorporating a liquidcrystal display device as shown in Embodiment Modes 1 to 3 in a framebody 2001. It is to be noted that a display screen 2002 is formed byusing a liquid crystal display device according to the presentinvention. In addition, a speaker 2003, operation switches 2004, and thelike are appropriately provided.

A TV set that is thinner and cheaper than a conventional one can beprovided by manufacturing the TV set to include the liquid crystaldisplay device according to the present invention.

FIG. 5B is a video camera, which includes a main body 2101, a displayportion 2102, a sound input portion 2103, operation switches 2104, abattery 2105, an image receiving portion 2106 and the like. It is to benoted that the display portion 2102 is formed by using a liquid crystaldisplay device according to the present invention.

A video camera that is thinner and cheaper than a conventional one canbe provided by manufacturing the video camera to include the liquidcrystal display device according to the present invention.

FIG. 5C is a mobile computer, which includes a main body 2201, a cameraportion 2202, an image receiving portion 2203, an operation switch 2204,a display portion 2205 and the like. It is to be noted that the displayportion 2205 is formed by using a liquid crystal display deviceaccording to the present invention.

A mobile computer that is thinner and cheaper than a conventional onecan be provided by manufacturing the mobile computer to include theliquid crystal display device according to the present invention.

FIG. 5D is a player using a recording medium in which a program isrecorded (hereinafter referred to as a recording medium), which includesa main body 2401, a display portion 2402, a speaker portion 2403, arecording medium 2404, operation switched 2405 and the like. This playermake it possible to appreciate music and cinema, play games and connectto the Internet by using a DVD, a CD or the like as a recording medium.It is to be noted that the display portion 2402 is formed by using aliquid crystal display device according to the present invention.

A player that is thinner and cheaper than a conventional one can beprovided by manufacturing the player to include the liquid crystaldisplay device according to the present invention.

FIG. 5E is a digital camera, which includes a main body 2501, a displayportion 2502, an eye piece 2503, operation switches 2504, an imagereceiving portion (not illustrated) and the like. It is to be noted thatthe display portion 2502 is formed by using a liquid crystal displaydevice according to the present invention.

A digital camera that is thinner and cheaper than a conventional one canbe provided by manufacturing the digital camera to include the liquidcrystal display device according to the present invention.

FIG. 6 is one example of a cellular phone that includes a liquid crystaldisplay device according to the present invention. A liquid crystaldisplay device 2601 is incorporated in a housing 2602 to be detachable.The shape and the size of the housing 2602 can be changed appropriatelydepending on the size of the liquid crystal display device 2601. Thehousing 2602, in which the liquid crystal display device 2601 is fixed,is attached to a printed substrate 2603, and a module is built.

The liquid crystal display device 2601 is connected to the printedsubstrate 2603 through an FPC 2604. Over the printed substrate 2603, asignal processing circuit 2608 is provided, which includes a speaker2605, a microphone 2606, a transmit and receive circuit 2607, a CPU, acontroller and the like. This module, an input means 2609, and a battery2610 are combined and stored in a frame body 2611. A pixel portion ofthe liquid crystal display device 2601 is placed so as to be recognizedfrom an aperture that is formed in the frame body 2611.

A cellular phone that is thinner and cheaper than a conventional one canbe provided by manufacturing the cellular phone to include the liquidcrystal display device according to the present invention.

The cellular phone in accordance with the present embodiment mode can bechanged into various modes depending on a function or a purpose thereof.For example, even when the cellular phone has a plurality of the liquidcrystal display devices or has a hinged open and shut structure byappropriately separating a frame body into a plurality of frame bodies,the advantages described above can be obtained.

As described above, the present invention has a remarkably wideapplication range, and the invention can be applied to electronicdevices in various fields. In addition, the electronic devices in thepresent embodiment mode can be manufactured by using a structure thathas any combination of Embodiment Modes 1 to 3.

Embodiment Mode 5

The present embodiment mode shows examples of display devices that usethe liquid crystal display device as described in Embodiment Modes 1 to3. A rear-projection display device 801 shown in FIGS. 7A and 7Bincludes a projector unit 802, a mirror 803 and a screen panel 804. Inaddition, a speaker 805 and operation switches 806 may also be provided.The projector unit 802 is placed in the lower position of a frame body807 of the rear-projection display device 801, and projects light forshowing an image toward the mirror 803, based on an image signal. Therear-projection display device 801 displays an image that is projectedfrom the backside of the screen panel 804.

On the other hand, FIG. 8 shows a front-projection display device 301.The front-projection display device 301 includes a projector unit 302and a projection optical system 303. The front-projection display device301 projects an image on a screen placed in front and the like.

The structures of projector units that are applied to therear-projection display device 801 shown in FIGS. 7A and 7B and thefront-projection display device 301 shown in FIG. 8 will be describedbelow.

FIG. 9 is one structure example of a projector unit 901. The projectorunit 901 includes a light source unit 902 and a modulation unit 903. Thelight source unit 902 includes a light source optical system 904composed to include lenses and a light source lamp 905. The light sourcelamp 905 is stored in a frame body not to diffuse stray light. As thelight source lamp 905, for example, a high pressure mercury lamp, axenon lamp or the like is used, which is capable of emitting the largeamount of light. The light source optical system 904 is composed byappropriately including an optical lens, a film that has polarizingproperty, a film for controlling a phase difference, an IR film and thelike. Then, the light source unit 902 is placed so that emitted lightgoes into the modulation unit 903. The modulation unit 903 includes aplurality of liquid crystal display devices 906, dichroic mirrors 907,total internal reflection mirrors 908, a prism 909, and a projectionoptical system 910. Light emitted from the light source unit 902 isdivided into a plurality of light paths by the dichroic mirror 907.

The liquid crystal display device 906 is provided to each light path.Transmitted light is modulated by the liquid crystal display device 906,which is classified into a transmission type, based on an image signal.Light of each color transmitted through the liquid crystal displaydevice 906 goes into the prism 909 so that an image is displayed on ascreen through the projection optical system 910.

Since a phase difference film can be provided between an electrode and aliquid crystal in the liquid crystal display device according to thepresent invention, a liquid crystal display device can be more easilymade thinner and more lightweight than conventionally. Therefore, aninexpensive display device that is made thinner and more lightweight canbe provided.

A projector unit 1001 shown in FIG. 10 has a structure which is providedwith reflection type liquid crystal display devices 1002. The reflectiontype liquid crystal display device 1002 has a structure in which thepixel electrode in the liquid crystal display device in Embodiment Mode3 is formed by using aluminum (Al), Ti (titanium), an alloy of thesemetals or the like.

The projector unit 1001 includes a light source unit 1003 and amodulation unit 1004. The light source unit 1003 has the same structureas in FIG. 9. Light from the light source unit 1003 is divided into aplurality of light paths by dichroic mirrors 1005 and 1010, and goesinto a polarizing beam splitter 1007, 1011 or 1012. The polarizing beamsplitter 1007 is provided with respect to the reflection type liquidcrystal display device 1002 corresponding to each color. The reflectiontype liquid crystal display device 1002 modulates transmitted lightbased on an image signal. Light of each color that is reflected by thereflection type liquid crystal display device 1002 goes into a prism1008, and is projected through a projection optical system 1009.

Of light that is emitted from the light source unit 1003, only light ofa wavelength range of red light is transmitted through the dichroicmirror 1005, and light of a wavelength range of green and blue light isreflected by the dichroic mirror 1005. Further, only light of awavelength range of green light is reflected by the dichroic mirror1010. The light of a wavelength range of red light, which has beentransmitted through the dichroic mirror 1005, is reflected by the totalinternal reflection mirror 1006, and goes into the polarizing beamsplitter 1007. in addition, the light of a wavelength range of greenlight goes into the polarizing beam splitter 1011, and the light of awavelength range of blue light goes into the polarizing beam splitter1012. The polarizing beam splitter 1007 has a function of dividingincident light to a P-polarized component and an S-polarized component,and a function of transmitting only the P-polarized component. Thereflection type liquid crystal display device 1002 polarizes incidentlight based on an image signal.

Only the S-polarized component corresponding to each color goes into thereflection type liquid crystal display device 1002 corresponding to eachcolor. The reflection type liquid crystal display device 1002 operatesin an electrically controlled birefringence mode (ECB). In addition, aliquid crystal molecule is orientated perpendicularly at an angle to asubstrate. Therefore, in the reflection type liquid crystal displaydevice 1002, the liquid crystal molecule is orientated so that incidentlight is reflected with no change in polarizing state when a pixel is inan OFF state. In addition, when a pixel is in an ON state, theorientation state of the liquid crystal molecule is changed and thepolarizing state of incident light is changed.

The projector unit 1001 shown in FIG. 10 can be applied to therear-projection display device 801 shown in FIGS. 7A and 7B and thefront-projection display device 301 shown in FIG. 8.

Projector units shown in FIGS. 11A to 11C have a single-plate structure.The projector unit shown in FIG. 11A includes a light source unit 1101,a liquid crystal display device 1102 and a projection optical system1103. The projection optical system 1103 is composed of one or aplurality of lenses. The liquid crystal display device 1102 is providedwith a color filter.

FIG. 11B shows the structure of a projector unit which operates in afield sequential mode. The field sequential mode is a mode in whichlight of each color such as red, green and blue is made go into a liquidcrystal display device sequentially with a time lag, and color displayis conducted without a color filter. In particular, when the fieldsequential mode and a fast-response liquid crystal display device arecombined, high-definition images can be displayed. In FIG. 11B, a rotarycolor filter plate 1304 provided with a plurality of color filters forred, green and blue is provided between a light source unit 1301 and aliquid crystal display device 1302. In this case, no color filter isprovided inside the liquid crystal display device 1302.

A projector unit shown in FIG. 11C has a structure of a color separationsystem that uses a micro lens as a color display system. In this system,a micro lens 1402 is provided on a light incidence side of a liquidcrystal display device 1403, and light of each color is illuminated fromeach direction to accomplish color display. In this case, no colorfilter is provided inside the liquid crystal display device 1403. In aprojector unit that employs this system, no light is lost due to a colorfilter, and thus, the projector unit has a feature that light from thelight source unit 1401 can be used effectively. The projector unitincludes a dichroic mirror 1404, a dicroic mirror 1405 and a dichroicmirror for R 1406 so that light of each color is illuminated from eachdirection to the liquid crystal display device 1403.

Since a phase difference film can be provided between an electrode and aliquid crystal in the liquid crystal display device according to thepresent invention, a liquid crystal display device can be more easilymade thinner and more lightweight than conventionally. Therefore, alsoas for a display device that is provided with a single-plate projectorunit, an inexpensive display device that is made thinner and morelightweight can be provided.

Although the present invention has been fully described by way ofembodiment modes with reference to the accompanying drawings, it is tobe understood that various changes and modifications will be apparent tothose skilled in the art. Therefore, unless otherwise such changes andmodifications depart from the scope of the present invention hereinafterdescribed, they should be construed as being included therein.

This application is base on Japanese Patent Application serial no.2004-315892 filed in Japanese Patent Office on Oct. 29, 2004, thecontents of which are hereby incorporated by reference.

1. A liquid crystal display device comprising a pixel, the pixelcomprising: a thin film transistor over a first substrate; an insulatingfilm over the thin film transistor, the insulating film comprising anopening; a transparent pixel electrode electrically connected to thethin film transistor; a first layer over and in contact with thetransparent pixel electrode in the opening, the first layer comprising aresin; a liquid crystal layer over and in contact with the first layer;an orientation film over and in contact with the liquid crystal layer; atransparent opposing electrode over and in contact with the orientationfilm; and a second substrate over the transparent opposing electrode,wherein, in a region which overlaps with the opening, the whole of theorientation film is substantially flat.
 2. The liquid crystal displaydevice according to claim 1, wherein the resin is an UV-cured resin. 3.The liquid crystal display device according to claim 2, wherein theUV-cured resin is an acrylic resin.
 4. The liquid crystal display deviceaccording to claim 1, further comprising a color filter over and incontact with the transparent opposing electrode.
 5. The liquid crystaldisplay device according to claim 1, wherein the liquid crystal displaydevice is a transmission type liquid crystal display device.
 6. A liquidcrystal display device comprising a pixel, the pixel comprising: a thinfilm transistor over a first substrate; an insulating film over the thinfilm transistor, the insulating film comprising an opening; atransparent pixel electrode electrically connected to the thin filmtransistor; a first layer over and in contact with the transparent pixelelectrode in the opening, the first layer comprising a resin; a liquidcrystal layer over and in contact with the first layer; a second layerover and in contact with the liquid crystal layer, the second layercomprising the resin; a transparent opposing electrode over and incontact with the second layer; and a second substrate over thetransparent opposing electrode, wherein, in a region which overlaps withthe opening, the whole of the second layer is substantially flat.
 7. Theliquid crystal display device according to claim 6, wherein, in theregion which overlaps with the opening, the second layer is wholly incontact with the transparent opposing electrode.
 8. The liquid crystaldisplay device according to claim 6, wherein the resin is an UV-curedresin.
 9. The liquid crystal display device according to claim 8,wherein the UV-cured resin is an acrylic resin.
 10. The liquid crystaldisplay device according to claim 6, further comprising a color filterover and in contact with the transparent opposing electrode.
 11. Theliquid crystal display device according to claim 6, wherein the liquidcrystal display device is a transmission type liquid crystal displaydevice.
 12. A method for manufacturing a liquid crystal display device,the method comprising the steps of: forming a thin film transistor overa first substrate; forming, over the thin film transistor, an insulatingfilm having an opening; forming a transparent pixel electrodeelectrically connected to the thin film transistor; applying a polymerover the transparent pixel electrode; curing the polymer; forming atransparent opposing electrode over a second substrate; forming anorientation film over the transparent opposing electrode; and attachingthe first substrate and the second substrate with each other with aliquid crystal layer interposed therebetween, wherein the orientationfilm is formed so that, in a region which overlaps with the opening, thewhole of the orientation film is substantially flat.
 13. The methodaccording to claim 12, wherein the curing is carried out by irradiatingthe polymer with UV light.
 14. The method according to claim 12, whereinthe cured polymer is an acrylic resin.
 15. The method according to claim12, further comprising a step of forming a color filter between thetransparent opposing electrode and the second substrate.
 16. The methodaccording to claim 12, wherein the liquid crystal display device is atransmission type liquid crystal display device.
 17. A method formanufacturing a liquid crystal display device, the method comprising thesteps of: forming a thin film transistor over a first substrate;forming, over the thin film transistor, an insulating film having anopening; forming a transparent pixel electrode electrically connected tothe thin film transistor; applying a polymer over the transparent pixelelectrode; curing the polymer; forming a transparent opposing electrodeover a second substrate; forming a second layer over the transparentopposing electrode, wherein the second layer is formed by applying thepolymer over the transparent opposing electrode and then curing thepolymer; and attaching the first substrate and the second substrate witheach other with a liquid crystal layer interposed therebetween, whereinthe second layer is formed so that, in a region which overlaps with theopening, the whole of the second layer is substantially flat.
 18. Themethod according to claim 17, wherein the second layer is formed sothat, in the region which overlaps with the opening, the second layer iswholly in contact with the transparent opposing electrode.
 19. Themethod according to claim 17, wherein the curing is carried out byirradiating the polymer with UV light.
 20. The method according to claim17, wherein the cured polymer is an acrylic resin.
 21. The methodaccording to claim 17, further comprising a step of forming a colorfilter between the transparent opposing electrode and the secondsubstrate.
 22. The method according to claim 17, wherein the liquidcrystal display device is a transmission type liquid crystal displaydevice.